ZSCAN4

February 25, 2025 Publication Data published in NEJM Evidence detail the first clinical test of ZSCAN4 for telomere elongation. Treatment with EXG-34217 resulted in in vivo telomere elongation in a subpopulation of lymphocytes to the normal range for age and increases in absolute neutrophil count in two patients. No treatment-related adverse events were observed. U.S. FDA has recently granted Rare Pediatric Disease Designation, Regenerative Medicine Advanced Therapy (RMAT) Designation, and Orphan Drug Designation to EXG-34217 for the treatment of patients with Telomere Biology Disorders. BALTIMORE, February 25, 2025 – Elixirgen Therapeutics, Inc., a clinical-stage biotechnology company focused on treating rare diseases, today announced publication of encouraging early clinical data from an ongoing Phase 1/2 trial (NCT04211714) demonstrating the first-ever successful sustained telomere elongation in two EXG-34217-treated patients with a telomere biology disorder (TBD). No treatment-related safety concerns were observed over a 24-month and 5-month period after EXG-34217 infusion. The full article published in NEJM Evidence, entitled, “Clinical Use of ZSCAN4 For Telomere Elongation in Hematopoietic Stem Cells,” can be accessed here. “The data published today in NEJM Evidence demonstrates sustained telomere elongation in blood cells in patients with TBDs without toxicity, an outcome that has not been achieved by other treatments for those with this disorder,” said Kasiani C. Myers, MD, Professor, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, and principal investigator in the study. “In addition, EXG-34217 administration did not require a preconditioning regimen or immunosuppression typically required for other treatment regimens, which is critical in this radiation- and chemotherapy-sensitive population. There is a significant unmet need in this space since the only option for patients with TBDs who develop bone marrow failure is hematopoietic stem cell transplantation (HSCT), which can result in life-threatening complications. We look forward to enrolling additional patients, now including pediatric patients over 12 years of age, in the trial.” Aki Ko, chief executive officer of Elixirgen Therapeutics, added, “ZSCAN4 was originally identified and characterized by our chief scientific officer, Minoru Ko, MD, PhD, at National Institute on Aging (NIA), one of the Institutes of the National Institutes of Health (NIH), and we are excited to share initial results of the first clinical trial providing ZSCAN4 to patients. This unique gene plays a critical role in several key genomic functions, including telomere extension, to restore the integrity and potency of stem cells. EXG-34217 harnesses the power of this protein and allows us to provide a potential new treatment option for TBDs. This therapy is genotype and mutation-independent since elongation of telomeres by ZSCAN4 is telomerase-independent. We’re pleased with these new data and look forward to continuing to work with Dr. Myers and the team at Cincinnati Children’s to advance the trial and are deeply appreciative of the patients who have participated.” Enrollment is currently open for participants aged 12 and older, regardless of gender or ethnicity, in the Phase 1/2 study (NCT04211714) evaluating EXG-34217 in patients with TBDs with bone marrow failure. Key study highlights include: Published results are from two patients following treatment with EXG-34217, one was followed up to 24 months and the other up to five months. Treatment resulted in telomere extension of CD34+ cells ex vivo for both patients. In one patient, treatment was associated with a change in the mean absolute neutrophil count (ANC) from 1.78×103/µl to 3.18×103/µl. A subpopulation of lymphocytes’ telomere length changed from 3.6 kb to 6.7 kb (50th percentile for age). The second patient, who required intermittent injection of low-dose G-CSF to maintain neutrophil counts, has not required G-CSF injection since the EXG-34217 treatment and has remained without prior symptoms of fatigue, aphthous ulcers, or bone pain at the last follow-up visit of month five. The EXG-34217 treatment was associated with a change in the lowest ANC from 0.6×103/µl to 1.2×103/µl without G-CSF injections. At month 3, a subpopulation of granulocytes with 5.8 kb telomere length emerged from granulocytes with 4.9 kb telomere length. No treatment-related adverse events were observed in patients after EXG-34217 infusion. These data support further investigation into the potential of EXG-34217 to treat patients with TBDs as a potential therapeutic intervention for preventing or treating bone marrow failure. About Telomere Biology Disorders and EXG-34217 Telomere biology disorders (TBDs) are a group of rare genetic conditions characterized by very short telomeres, the protective end caps of chromosomes that shorten with age. TBDs, such as dyskeratosis congenita, can lead to serious conditions including bone marrow failure due to severely affecting the ability of hematopoietic stem cells (HSCs) to produce blood cells. EXG-34217 is a dose of autologous CD34+ HSCs that have transiently expressed Zinc finger and SCAN domain containing protein 4 (ZSCAN4), a protein responsible for regulating telomere elongation and genome stability that can lengthen telomeres independently of telomerase. TBDs affect approximately 1 in 1 million people in the U.S. About Elixirgen Therapeutics, Inc. Elixirgen Therapeutics, Inc. is a clinical-stage biotechnology company focused on the treatment of rare diseases and aging-associated diseases using its ZSCAN4 technology and mRNA platform technologies. For more information, visit ElixirgenTx.com. Forward-Looking Statements This press release may contain “forward-looking” statements. Actual results may differ materially from those set forth in this press release due to the risks and uncertainties inherent in pharmaceutical research and development. Any forward-looking statements in this press release speak only as of the date of this press release, and Elixirgen Therapeutics undertakes no obligation to update or revise the statements in the future, even if new information becomes available. Contact Media Relations: LifeSci Communications 603-714-2638 Share:

February 20, 2025 Press Release BALTIMORE, February 20, 2025 – Elixirgen Therapeutics, Inc., a clinical-stage biotechnology company focused on treating rare diseases, today announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to EXG-34217, a gene therapy for treatment of Telomere Biology Disorders (TBDs). EXG-34217 is currently being studied in an ongoing Phase 1/2 trial (NCT04211714) for the treatment of patients with TBDs with bone marrow failure. Enrollment is currently open for participants aged 12 and older, regardless of gender or ethnicity. The FDA recently granted EXG-34217 Rare Pediatric Disease Designation (RPDD) and Regenerative Medicine Advanced Therapy (RMAT) Designation. The FDA grants Orphan Drug Designation to support the development of investigational therapies intended for treatment, prevention, or diagnosis of a rare disease or condition. The Orphan Drug Designation qualifies Elixirgen Therapeutics’ EXG-34217 program for various incentives that assist in the drug development process including tax credits, grants, a waiver of certain administrative fees for clinical trials, and the potential for seven years of market exclusivity following drug approval. About Telomere Biology Disorders and EXG-34217 Telomere biology disorders (TBDs) are a group of rare genetic conditions characterized by very short telomeres, the protective end caps of chromosomes that shorten with age. TBDs, such as dyskeratosis congenita, can lead to serious conditions including bone marrow failure due to severely affecting the ability of hematopoietic stem cells (HSCs) to produce blood cells. EXG-34217 is a dose of autologous CD34+ HSCs that have transiently expressed Zinc finger and SCAN domain containing protein 4 (ZSCAN4), a protein responsible for regulating telomere elongation and genome stability that can lengthen telomeres independently of telomerase. TBDs affect approximately 1 in 1 million people in the U.S. About Elixirgen Therapeutics, Inc. Elixirgen Therapeutics, Inc. is a clinical-stage biotechnology company focused on the treatment of rare diseases and aging-associated diseases using its ZSCAN4 technology and mRNA platform technologies. For more information, visit ElixirgenTx.com. Forward-Looking Statements This press release may contain “forward-looking” statements. Actual results may differ materially from those set forth in this press release due to the risks and uncertainties inherent in pharmaceutical research and development. Any forward-looking statements in this press release speak only as of the date of this press release, and Elixirgen Therapeutics undertakes no obligation to update or revise the statements in the future, even if new information becomes available. Contact Media Relations: LifeSci Communications (603) 714-2638 Share:

February 13, 2025 Press Release BALTIMORE, Feb. 13, 2025 (GLOBE NEWSWIRE) — Elixirgen Therapeutics, Inc., a clinical-stage biotechnology company focused on treating rare diseases, today announced that the U.S. Food and Drug Administration (FDA) has granted Regenerative Medicine Advanced Therapy (RMAT) designation to EXG-34217, a gene therapy for treatment of Telomere Biology Disorders (TBDs). EXG-34217 is currently being studied in an ongoing Phase 1/2 trial (NCT04211714) for the treatment of patients with TBDs with bone marrow failure. Enrollment is currently open for participants aged 12 and older, regardless of gender or ethnicity. RMAT designation, established under the 21st Century Cures Act, is a dedicated program designed to expedite the drug development and review processes for promising pipeline products, including gene and cell therapies. A regenerative medicine therapy is eligible for RMAT designation if it is intended to treat, modify, reverse, or cure a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the therapy has the potential to address unmet medical needs for that disease. A treatment with RMAT designation receives all the benefits of Fast Track and Breakthrough Therapy designation programs, including early interactions with the FDA, which may be used to discuss potential surrogate or intermediate endpoints to support accelerated approval. About Telomere Biology Disorders and EXG-34217 Telomere biology disorders (TBDs) are a group of rare genetic conditions characterized by very short telomeres, the protective end caps of chromosomes that shorten with age. TBDs, such as dyskeratosis congenita, can lead to serious conditions including bone marrow failure due to severely affecting the ability of hematopoietic stem cells (HSCs) to produce blood cells. EXG-34217 is a dose of autologous CD34+ HSCs that have transiently expressed Zinc finger and SCAN domain containing protein 4 (ZSCAN4), a protein responsible for regulating telomere elongation and genome stability that can lengthen telomeres independently of telomerase. TBDs affect approximately 1 in 1 million people in the U.S. About Elixirgen Therapeutics, Inc. Elixirgen Therapeutics, Inc. is a clinical-stage biotechnology company focused on the treatment of rare diseases and aging-associated diseases using its ZSCAN4 technology and mRNA platform technologies. For more information, visit ElixirgenTx.com. Forward-Looking Statements This press release may contain “forward-looking” statements. Actual results may differ materially from those set forth in this press release due to the risks and uncertainties inherent in pharmaceutical research and development. Any forward-looking statements in this press release speak only as of the date of this press release, and Elixirgen Therapeutics undertakes no obligation to update or revise the statements in the future, even if new information becomes available. Contact Media Relations: LifeSci Communications 718-483-4440 Share: